Tool retainer for rock drills



March 7, 1950 E. B. LEAR TOOL RETAINER FOR ROCK DRILL-S Filed Feb. 1,1947 JNVENTOR. E421. 5. EAR,

Patented Mar. 7, 1950 UN I TED STATES OFFICE T0013 REI-AINER FOR 'ROCKDRILLS' 'EarlB. Lear,;Detroit,-,Mich., assignor toChicago Pneumatic Tool1 Company, New vYork,.N .r Y.,. acorporation of New Jersey.

Application' February '1, 1947;Serial No. 725,841

SCIaimS. .(Cl. 279-491) This invention relates; toretainersforrpercussive -tools,.and more particularly .to a retainer forpreventing a working implement from-becoming accidentally detached fromthe tool in which ;it-

ment, suchas the drill steel of a rock drill, in-

both retaining and -.releasing positions the employment of resilientmeans so arranged-within the implement retainingmember thatathe latteris maintained in locked relationto the trunnions of the tool when ineither retainingwor releasing position; the provision"ofresili'ent'means in the implement retaining member-which, in additionto theforegoing function, serves-:as aqshock absorber at such: timesiasthe implement collar may be per-cussivelyzdriven against the, implementre-- taining means; and the provisionaof; a device which 'is' simple inconstruction and inexpensive to, manufacture:

Other objects and features of the invention will be more clearly,pointed outin" the followingdescription and appended claims.

In the accompanyingdrawing:whichiillustrates one embodiment of the,invention:

Fig. 1 isa front view, .partly in elevation:- and partly in section;ofva fragmentary portion 'Ofgfi percussive tool embodying the invention;

Fig. 2 isa side view,'par tly' in elevationand partly in section; asindlcatedby the arrows2-.2

in Fig. 1, the releasing-positioncf the latching member being indicatedin broken lines;

Fig. 3 is a viewlooking upwardly, as; indicated by the arrows 3-4)in"Fig..1, -showing the percussive tool in elevation and the drillsteelin cross-section;

Fig. 4 is an end view of the bufier detached from the-assembly;

Fig. 5 isian end view ofa shoe forming part of the retainer;

Fig. 6 isa longitudinalsection viewof' the shoe,

is of polygonal cross-section and has a sliding fit with the chuck. Theupper end of the shank is adapted to-receive blows delivered by a pistonextension 1.6. .The structuredescribed up to this point: isconventional.

In. accordance with-the present invention, and asbest' shown-in Fig; 1,front head I4 is provided withapair of lugs I"! which extendlaterallyfrom its forward; endi-to' serve' as: supports for a pair offorwardlyleading trunnion carriers I8. Each lug is formed withia front or: lowerflat surface itaand'a rear or'upper flat'surface 2! which are adapted toiservetas-rseats for the mountingof a trunnion carrier.Alongitudinalbore 22 extends I through each luglfor the; accommodationof the shankl23 of a carrier, the free-end of each carrierbeingthreaded: for the receptionof a nut 2:3. Each carrier is vprovided'witha retainer flange or." collar" 25 which is brought .into rigidabutment'with the'front-seat' iii of the lug by the tightening of nut 2dagain'stthe rear seat 2!; of the lug. The: assembly of the carriers inrigid and: immovable relation tothe lugs is an importantfeature of theinvention. The forward end :of each carrier has a trunnion 26 integraltherewith and directed inwardly to termimate in spacedrelation with theopposite trunnion; Each trunnion hasa top or rear latching fiat2'l, anda side latchingfiat 28 arranged. to

seat the: shoe 29;..as hereinafter more fully de scribed. The twotrunnions are disposed coaxially-and the'major gportion of'their surfaceis cylindrical.

Supported .by'thetrunnions 26- is a latching member 3| provided with ahandle 32 and im-- plement retainer'means in the form of a yoke 33. Yoke33 is adapted topartially surround the drill steel It or similar workingimplement (Fig.

3) andis formedlat its rear or upper portion witha flat surfacezfi iadapted toseat 'thecollar l I of the=drill steel. The main body of thelatching member has-a transverse-aperture 35,-.the opposite. sides ofwhich are: flat to form walls :36 (Fig; -2)1-and"the'top' 31 and bottom38 of which are rounded. .Top 37 and'bottom '38 are each in theshapeiof' a, half-cylinder and form, respectively, aseat; for the buffer35 andra bearing for the'latchingmember 3lto-rotate upon the trunnions'.Thebu'ffer is-rma'de of an oil resistant resilient materialiofi thesynthetic group, such as Duprene and is mounted in pre-compressionwithinthe'aperture35: Such buffer is formed with arounded portion toconform to the rounded top' portion of the transverse aperture of thelatch andhas fiatssi-de walls-to conform to theupper side walls of thelatch aperture. Opposite the rounded portion, the buffer has a flat base3| which rests upon the flat upper face 42 of the shoe 29. A transverseaperture 43 is formed to extend through the buffer to allow forresilient compression of the buffer in response to the movement of thelatching member from open or unlatched to closed or latched position.When the buffer is detached from the assembly and in a condition ofnormal expansion, the aperture 43 is cylindrical (Fig. 4) but when thebuffer is mounted under pre-compression, the aperture assumes anellipsoidal shape (Fig. 2).

Shoe 29 is of steel or other suitable material and is preferably bondedto the buffer. Said shoe extends transversely of the latching member 3|and its end walls are coterminus with the end walls of the main body ofthe latching member and of the buffer. The outer portions of the shoe(Figs. 5, 6 and 7) are formed with concave arcuate recesses 44 toconform to the periphery of the trunnions thereby to provide a rotarycooperation between the shoe 29 and the trunnions 29 upon the alternatemovement of the latching member from open to closed position. Eachtrunnion has an inner side flat 45 (Fig. 2) so that the trunnions may bereversed in position whenever the corner becomes worn. To reverse theposition of the trunnions, it is only necessary to loosen nuts 24 andremove the trunnions and latching member as a unit from the front head.This sub-assembly is then disassembled, the trunnions reversed, theparts re-assembled and remounted on the front head.

Each carrier i8 is formed with a flange 4B, the inner face 41 of whichloosely abuts the flat sides 48 of the latching member 3| and the endfaces 49 of the shoe 29 to prevent the yoke from being shifted out ofalignment with the drill steel and to confine the shoe in operativeposition in reference to the trunnions.

In operation, the latching member 3| maybe set in two rotative positionsrelatively to the working implement Ill, and is held respectively inlatched position to prevent the removal or ejection of the implementfrom the tool or in unlatched position to permit the insertion orremoval of the implement by the operator. When it is desired to insertthe implement it: into the tool, or to remove it therefrom, the latchingmember 3| is unlatched or set to the position shown by the bro-ken linesin Fig. 2. Clearance is thereby provided for the insertion or removal ofthe working implement from the tool chuck l2. Upon insertion of theimplement in the chuck, the latching member is locked by throwing itshandle 32 inwardly and rearwardly in clockwise direction to the positionshown in solid lines in Fig. 2 so that the shoe 29 is moved from itsdotted line position rotatively to its solid line position or from itsposition in contact with the side flat 28 of the trunnions to a positionin contact with the upper or rear flat 21 of the trunnions. Theresilience of the buffer 39 and the provision of the aperture 43 thereinpermit of its compression to allow the shoe to pass from one position tothe other over the corner 5| (Fig. 8) of the trunnions. Corners 5| arebevelled to allow for easier and smoother passage of the shoe. When theshoe is in either position, the resilience of the buffer will force theshOe against the upper flats 21 or against the side flats 28, as thecase may be, to maintain it in locked position. Upon such movement ofthe latching member, the yoke will be brought downwardly or forwardly,as shown in Fig. 2, to par- 4 tially surround the working implement andthe yoke flat or seat 34 is thus brought into the path of collar of theimplement. In such latched or locked position, the forward or downwardmovement of the working implement is limited by engagement of the collarII with the seat 34 and the implement is thus positively prevented frombeing ejected from the tool during operation or from falling out of thefront head while at rest.

It should also be observed that the latching member 3| is so disposed,when in latched position, that any blows transmitted through the collarto the yoke 33 will be absorbed by the resilient buffer or cushion 39.This will occur, for ex ample, at times when the operator may lift theentire tool from the surface on which it is operating without shuttingoff the driving power, or when the working implement Ill may becomestuck or held against further movement in such working surface, or incase the power is turned on by accident when the tool is not in use.Thus the buffer 39 functions resiliently not only to compress the shoe29 into locking engagement with the trunnion flats 28 and 21 to hold thelatching member in retaining and releasing position respectively butalso as a shock absorber or cushion. A further advantage of thisarrangement of the buffer 39 is that the trunnion carriers |8 may berigidly and immovably secured to the front head I4 so that whenever thecollar H of the working implement ||l strikes the yoke 33, the latchingmember 3| will be the only element to move in absorbing the shock. Inrelevant prior art, the whole retainer assembly including the trunnionsmove, thereby causing considerable wear to develop in the assembly.

What is claimed is:

1. In a power operated percussive tool having a front head and acollared working implement supported therein, a retainer for saidimplement comprising trunnions rigidly associated with the front headand directed inwardly thereform in axial alignment with each other, alatching member mounted on the trunnions for limited relative movementparallel to the implement and adapted to be moved at will into retainingand releasing positions, means for yieldably locking the latching memberin selected positions including a plurality of flat surfaces on eachtrunnion, and means on the latching member movable into the path of thecollared implement to retain said implement in operative position andmovable out of said path to release said implement, said yieldablelocking means including a resilient member arranged between the latchingmember and trunnions to absorb the energy of impact of the collaredimplement on the latching member and prevent transmission thereof to thetrunnions.

2. A retainer for a collared implement of a power operated percussivetool comprising a pair of carrier members adapted to be mounted on thefront head of the tool, a pair of trunnions on the carrier membersdirected inwardly therefrom in axial alignment with each other andhaving looking means thereon including flat surfaces said trunnionsbeing interchangeable each with the other, a centrally aperturedlatching member mounted on the trunnions between the carrier members andmovable alternately into implement retaining and releasing positions,the apel' ture in the latching member being elongated to permit limitedforward movement of the latching member relative to the trunnions, meanson the latching member movable into the path of the collared implementto retain said implement in operative position and movable out of saidpath to release said implement, and resilient means so disposed withinthe rear part of the aperture of the latching member as to yieldablylock the latching member in retaining and releasing positions upon saidflat surfaces upon predetermined movement of the latching means, saidmeans being also adapted to urge the latching member toward its extremerearward position relative to the trunnions and allow forwarddisplacement of the latter to absorb the shocks of blows of the collaredimplement whenever the latter is percussively driven against thelatching member.

3. An implement retainer, according to claim 2, in which the resilientmeans comprises a shoe having a surface adapted to cooperate with theflat surfaces on the trunnions and a resilient bufier adjacent the shoeadapted to yieldably lock the shoe in latched engagement with the fiatsurfaces.

4. In an implement retainer for a power operated percussive tool, incombination with a front head and a collared working implement, a pairof carrier members, trunnions on the carriers directed inwardlytherefrom in axial alignment with each other and terminating in spacedrelation to each other, a latching member rotatably mounted on thetrunnions and disposed between the carriers, said member having anelongated central aperture for the reception of the trunnions at theforward end of the aperture, locking means on each trunnion including aplurality of flat surfaces, a shoe arranged within the central apertureat the rear of the trunnions, resilient means arranged adjacent the shoewithin the rear part of said central aperture adapted to press said shoeagainst the flat surfaces of the trunnions thereby to yieldably lock thelatching member in retaining and releasing positions and to hold thelatching member normally in its rearmost position, said resilient meansbeing also adapted to yield to permit th latching member to move forwardand to absorb the shock of blows of the collared implement whenever thelatter is percussively driven against the latching member thuspreventing the transmission of impacts to the trunnions, and a yoke onthe latching member having a seating surface adapted to receive thecollar of the working implement when said yoke is moved into the path ofthe collar.

5. In a power operated percussive tool having a fronthead and a collaredworking implement supported therein, a retainer for said implementcomprising trunnions rigidly attached to the fronthead and directedinwardly therefrom in axial alignment with each other, a latching memberhaving an enlarged aperture receiving the trunnions loosely, thusallowing limited relative movement in forward and rearward directions,said latching member being movable about the axis of the trunnions intoselected retaining and releasing positions and having a portion movableinto and out of the path of the implement to retain or release thelatter, and means for yieldingly holding the latching member in selectedpositions on the trunnions, said holding means comprising a buiferdisposed in the rear part of said aperture and under compression to urgeand normally hold the latching member in its maximum rearward positionrelative to the trunnions, the buffer being arranged to absorb theforward impacts of the implement on the latching member while permittingthe latching member to move forwardly relative to the trunnions, thuspreventing the transmission of impact shocks from the latching member tothe trunnions.

EARL B. LEAR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,807,799 Slater June 2, 19312,230,046 Curtis Jan. 28, 1941

